Industrial-rated circuit breakers are currently available having operating components that are designed for automatic assembly to provide cost improvement as well as improved operating efficiency. The precision alignment performed by the automated assembly equipment assembles the operating components within very close operating tolerances. An operating mechanism designed for down-loaded automated assembly is described in U.S. Pat. No. 4,864,263, which Patent is incorporated herein for reference purposes. The operating mechanism assembly includes a pair of operating springs that are overcentered for rapidly driving the movable contact arm and the attached movable contact away from the stationary fixed contact to interrupt the circuit current. The operating mechanism includes a cradle operator which engages a latch assembly to prevent the movable contact arm from being driven to its open position under the urgence of the charged operating springs. The compact latch assembly includes a primary and secondary latch operating within a common support structure.
With higher ampere-rated industrial circuit breaker designs, the correspondingly larger operating springs provide a substantially increased latching force to the cradle operator within the operating mechanism such that a correspondingly larger "tripping" force is required to unlatch the cradle operator and release the operating mechanism. An earlier circuit breaker operating mechanism design utilizes a supplemental tripping mechanism in combination with the circuit breaker tripping mechanism to provide sufficient tripping force to articulate the operating mechanism. One such supplemental tripping mechanism is described within U.S. patent application Ser. No. 518,673 filed May 3, 1990, which Patent Application is incorporated herein for reference purposes.
One purpose of the instant invention is to provide a multiple latch assembly whereby the tripping force required to articulate the circuit breaker operating mechanism is reduced by means of the multiple latch arrangement.